1. Field of the Invention
The present invention relates to a pointing device and a locus smoothing method, and in particular to a pointing device with a locus smoothing function and a locus smoothing method appropriate for the pointing device.
2. Description of the Related Art
A mouse is a commonly used input device. A wheel mouse processes a displacement signal, a button signal, and an interface signal and communicates with a computer via a PS2 interface, a universal serial bus (USB) interface, or a wireless communication interface using the mechanical structure of its wheel and a micro-controller chip. An optical mouse replaces the mechanical structure of the wheel mouse with a complementary metal oxide semiconductor (CMOS) photo sensor chip capable of optical navigation. When a mouse moves, its displacement is output to a computer sequentially. While the displacement is digitized by the mechanical structure of the wheel mouse or the CMOS photo sensor chip of the optical mouse to be discrete, rather than continuous in original analog format. If the mouse moves at a small angle or an error occurs in the progress of digitization, a right angle is unavoidable in the locus of the mouse even if the mouse moves slowly and smoothly.
FIG. 1 shows a locus of movement of the conventional mouse. The conventional mouse outputs detected input displacements to a computer without any additional processing. As shown in FIG. 1, I indicates the origin of mouse movement, the input values of displacement are P11(1,0), P12(0,2), P13(2,0), P14(1,0), P15(0,3), P16(5,0), and P17(0,5), wherein each input value indicates the displacement from the previous to the current position. When the input values are sequentially output to the computer, the locus of movement of the conventional mouse is a zigzag with some right angles as shown in FIG. 1. This is unacceptable.